Lagriinae

Latreille, 1825

Long-jointed Beetles

Lagriinae is a of within the , comprising more than 270 grouped into 11 tribes. are -sized (5–12 mm) with characteristic Tenebrionidae features including a 5-5-4 tarsal formula and antennal bases concealed by . The subfamily is notable for its defensive with Burkholderia bacteria that produce the antifungal compound lagriamide, protecting and from antagonistic . This symbiosis has evolved through multiple independent horizontal acquisition events rather than strict co-diversification.

Statira dolera by (c) jimeckert49, some rights reserved (CC BY). Used under a CC-BY license.

Statira nigromaculata by (c) Katja Schulz, some rights reserved (CC BY). Used under a CC-BY license.

Statira nigromaculata by (c) jimeckert49, some rights reserved (CC BY). Used under a CC-BY license.

Pronunciation

How to pronounce Lagriinae: //ləˈɡriː.ɪ.naɪ//

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Identification

Distinguished from other by the combination of: deeply that often partially surround antennal bases; last antennal enlarged (longest or widest); at least as broad as , often constricted behind eyes; pronotum narrower than elytral base, broadest at base with sinuate sides. The 5-5-4 tarsal formula and concealed antennal bases are -level characters shared with other Tenebrionidae. Some are mimics of other families: Arthromacra resembles , Rhypasma resembles , Casnonidea apicicornis resembles , Statira resembles , and Paratenetus punctatus resembles .

Images

Appearance

are mostly -sized, 5–12 mm in length. They exhibit typical characteristics: 5-5-4 tarsal formula (five on fore- and midlegs, four on hind legs) and antennal bases concealed by ( projections of the ). are usually deeply (notched) and in many partially surround the antennal bases. The last antennal is either the longest or widest segment, often sexually . The head tends to be at least as broad as the and is often constricted behind the level of the eyes. The pronotum is generally much narrower than the base of the , broadest at its base, with sinuate or otherwise constricted sides. Some species display pronounced , including (wingless) females in certain subgenera.

Habitat

Associated with vegetation; occur in decaying vegetation, stumps, and under bark. found on plants, with some noted as pests (e.g., soybean). -harboring species can be found on plants and in soil environments where symbiotic Burkholderia bacteria can be acquired.

Distribution

distribution with records from all major biogeographic regions. Documented from Brazil, Japan, Germany, Spain, Australia, Morocco, Algeria, China (including Tibet, Guangxi, Guizhou, Hong Kong, Hunan, Sichuan), and North America.

Diet

feed in decaying vegetation. Specific feeding habits are not well documented; Lagria villosa is noted as a soybean pest, suggesting .

Host Associations

Burkholderia - defensive -eroded bacteria producing antifungal lagriamide; housed in glandular structures of female and secreted onto
Antagonistic fungi - target of defenseLagriamide protects and from fungal
Soybean and other plants - Site of transfer; symbionts can survive on tissues for several days
Soil microbiota - potential sourceEnvironmental acquisition of possible from soil and environment

Life Cycle

are deposited with symbiotic Burkholderia bacteria secreted from glandular structures associated with the female . develop in decaying vegetation, stumps, and under bark. protect both egg and larval stages from antagonistic . Specialized symbiont-harboring structures likely evolved between 55–82 million years ago based on fossil evidence.

Behavior

Females secrete defensive onto during . Some exhibit pronounced with females. Certain (e.g., Eleodes relatives within ) perform characteristic 'headstand' defensive postures when disturbed, though this is more documented in related tenebrionid groups.

Ecological Role

Defensive with Burkholderia protects early from fungal . Some are agricultural pests (e.g., on soybean). role in larval stage processing decaying vegetation. Symbiont transfer to and from tissues may influence plant-associated microbial .

Human Relevance

Some are pests, notably Lagria villosa on soybean. Subject of significant research interest regarding evolution of defensive , , and erosion in bacterial . The lagriamide biosynthetic has potential biotechnological applications.

Similar Taxa

AlleculinaeFormerly separate , now of ; that do not resemble 'classic'
ZopheridaeFormerly included in ; with extremely heavily sclerotized that are difficult to pin
OedemeridaeConvergent resemblance: Arthromacra (Lagriinae) resembles members of this
SilvanidaeConvergent resemblance: Rhypasma (Lagriinae) resembles members of this
ChrysomelidaeConvergent resemblance: Casnonidea apicicornis (Lagriinae) resembles members of this
CarabidaeConvergent resemblance: Statira (Lagriinae) resembles members of this
CoccinellidaeConvergent resemblance: Paratenetus punctatus (Lagriinae) resembles members of this

More Details

Symbiont Evolution

The lagriamide-producing represents a dynamic evolutionary with at least four independent horizontal acquisition events of closely related Burkholderia across 7 from 5 countries on 4 continents. This contrasts with the pattern of strict and host-symbiont co-diversification seen in older intracellular symbioses. Each independent acquisition was followed by convergent erosion in the symbiont lineage.

Genome Erosion

The Burkholderia in Lagriinae show extensive reduction including loss of repair , primary metabolism genes, and accumulation of pseudogenes and transposases. Despite this erosion, the lagriamide biosynthetic gene cluster is retained and functional. -associated Burkholderia relatives retained large genomes but secondarily lost the lagriamide gene cluster.

Taxonomic History

Lagriinae was formerly treated as a separate (Lagriidae) but is now classified as a of . The group includes more than 270 organized into 11 tribes, with significant diversity in Asia, Africa, and the Americas.